On Sun, Nov 30, 2014 at 7:06 PM, Sam Varshavchik <[email protected]>
wrote:
> Jan Ingvoldstad writes:
>
> On Sun, Nov 30, 2014 at 3:19 PM, Sam Varshavchik <<URL:mailto:
>> [email protected]>[email protected]> wrote:
>>
>> At some point, I suppose that the junk senders will wise up and will
>> prudently set up their spam spewers, and at that point this check will
>> lose its usefulness. But, until that happens, this is very useful.
>>
>> So that would be until around 2008, then? :)
>>
>> Spammers wisened up a long time ago, and are using a wide range of tricks
>> to send their messages.
>>
>
> But not all of them. Like I said, right now this check stops a huge volume
> of crap.
>
> I just checked my logs, and last week, the HELO check stopped over 500
> spam delivery attempts.
That's nice. Over here, 500 spam delivery attempts would pass right under
the radar, since we're seeing tens of millions of spam delivery attempts.
Some of these get a nice plus score because the HELO value is incomplete or
contains an IP address instead of an FQDN.
On our side, we had to turn off a SpamAssassin rule called SPF_HELO_PASS,
because it essentially gave a negative score to spam, ensuring that it
passed other filters.
For those that create warnings about possibly forged, but otherwise valid
HELO addresses, there are around 600-700k per week.
Non-resolving sender addresses are around 400-500k, around 10% of these
overlap with warnings about possibly forged HELO addresses.
Spamhaus and other blacklists take care of around 1.5 million per week.
These take care of the most of the possibly forged HELO addresses that are
spam.
Various scoring rules combined take care of most of the rest.
Still, a lot of spam does get through these days, but I wouldn't want to
reject hundreds of thousands of messages weekly just because someone had a
mismatch in their setup.
--
Jan
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